Anti-psychotic medicine should not be the first option offered to people at risk of developing schizophrenia, researchers said on Friday.

Clinicians should be "extremely careful" about prescribing anti-psychotics to young people, because only a tenth will go on to develop more serious conditions, a study suggests.

The study by five universities found that "benign" psychological treatments, including Cognitive Therapy (CT), were effective in reducing the severity of psychotic experiences that can lead to conditions such as schizophrenia.

Published on the British Medical Journal website bmj.com, the study found the frequency, seriousness, and intensity of psychotic symptoms that may lead to more serious conditions was reduced by counselling and CT.

The landmark research could pave the way for coherent treatment for young people at risk of developing psychotic illnesses.

Teams from the universities of Glasgow, Birmingham, Cambridge and East Anglia, led by the University of Manchester, gave participants, aged between 14 and 35, weekly CT sessions for a maximum of six months, over a four year period.

They then monitored participants after treatment to track their symptoms.

Before the trial, international evidence estimated that 40-50% of people at risk of developing psychosis at a young age would progress to a psychotic illness.

But only 8% of patients in the study were shown to have made the transition.

Researchers said the results have led to suggestions that anti-psychotic medicine should not be the first option for young patients.

Professor Andrew Gumley, who led the research team at the University of Glasgow, said: "This study has very important implications for ensuring that young people who are at risk of developing psychosis are offered psychological therapy.

"Our findings that there is a much lower transition rate than previously found means that clinicians have to be extremely careful about prescribing anti-psychotics in this group since only one in 10 will actually develop psychosis."